Generally, an air conditioner has a throttle which may open and close the ports in a bulkhead of the air conditioner for exhausting a portion of indoor air blown by a blower. However, such air conditioners have a drawback that they can exhaust a proportion of recirculated indoor air but introduce little fresh outdoor air.
An improvement over the conventional air conditioner is disclosed in U.S. Pat. No. 4,553,404 to MALCHOW et al. wherein an air conditioner is provided with fresh air circulation means having a throttle which is selectively movable within a dual inlet air conditioner blower wheel between the inlets to control the volume of air flowing through the inlets and the proportions of indoor and outdoor air admitted. The air mixture is presented to the blower wheel and contrifugally propelled through an outlet to the space to be conditioned.
This structure is complicated and furthermore is not successful since the air conditioner can introduce the fresh outdoor air to the indoor air but cannot exhaust the recirculated indoor air from the air conditioner.